Many systems for controlling automotive engines require a measure of the pressure in the engine air inlet. In naturally aspirated engines, that pressure is substantially atmospheric or barometric pressure. To provide such a measure, barometric pressure sensors generally include an aneroid or other pressure sensitive member which responds to the difference between the inlet pressure and the pressure in an evacuated chamber. Because the absolute pressure in the evacuated chamber is near zero, the position of the pressure sensitive member indicates the absolute value of the inlet pressure.